Fluoroscopic computer-assisted pedicle screw placement through a mature fusion mass - An assessment of 24 consecutive cases with independent analysis of computed tomography and clinical data

Study Design. Observational matched cohort study with computed tomography (CT) analysis of pedicle screw placement. Objective. Assess the clinical accuracy of computer-assisted fluoroscopy for the placement of thoracolumbar pedicle screws through a mature posterolateral fusion mass. Summary of Background Data. Pedicle screw placement through an amorphous posterolateral fusion mass intuitively carries a higher risk of pedicle wall violation. Methods. Postoperative CT scans of 102 pedicle screws placed through a mature posterolateral fusion mass (n = 10 [T10-T12]; n = 92 [L1-S1]) were independently assessed and compared with a matched control (nonobscured anatomy) group. All screws were placed before any decompression using the FluoroNav system. Results. In the fusion mass group, overall 81.4% of screws were completely within the pedicle. Seven medial and 12 lateral pedicle breaches occurred. Relative to the total number of screws, pedicle breaches were graded II (< 2 mm) in 13.5%, III (2-4 mm) in 2.9%, and IV (> 4 mm) in 2.0% of screws. The number and direction of pedicle breaches were not significantly different when compared with the control group. There were no clinically significant screw misplacements in either group. Conclusions. The use of computer-assisted fluoroscopy is safe and effective for the placement of thoracolumbar (T10-S1) pedicle screws through a posterolateral fusion mass without performing laminoforaminotomies.